Find Duplicate number problem asked by GOOGLE

FindDuplicate.js

Problem Statement: You are given an array of length n + 1 whose elements belong to the set {1, 2, ..., n}. By the pigeonhole principle, there must be a duplicate. Find it in linear time and space.

Solution: 
// XOR operator will return 0 if it is applied even times on same number And return number itself when it is applied odd times on the same number.
function findDuplicate(Arr) {
  let len = Arr.length;
  let acutalXORResult = 0; // contains the XOR operation result for the actual values from 1 to n.
  let arrayXORResult = 0; // contains the XOR operation result on the array values.
  for(let count=0; count<len; count++) {
    acutalXORResult = acutalXORResult^count;
  }
  for(let count=0; count<len; count++) {
    arrayXORResult = arrayXORResult^Arr[count];
  } 
  // XOR b/w two result will calculate the duplicate value because XOR operation will occur for every value twice except duplicate value which will comes three times.
  console.log('Result = ', acutalXORResult^arrayXORResult);
}